1. High-Resolution Spectroscopy of the ν16 Band of 1,3,5-Trioxane
Bradley M. Gibson and Nicole Koeppen
Department of Chemistry, University of Illinois at Urbana-Champaign
Benjamin J. McCall
Departments of Chemistry and Astronomy, University of Illinois at Urbana-Champaign

2. Outline Motivations Previous Work Spectrometer Design CRDS Overview
Optical Layout
Observed Spectra
Future Work

3. Why study trioxane? C3v symmetry, chair conformation
Only one rotationally-resolved band observed
220 km/mol band at 1178 cm-1
Strong band would be useful for characterizing newly developed equipment
Figure from: M. Kobayashi et al., “Vibrational Spectra of Trioxane and Trioxane-d6” J. Chem. Phys. 44, 922 (1966)

4. Previous Studies
Numerous low-res vibrational spectra, including Kobayashi et al. in 1965
Microwave spectrum observed by Oka et al. in 1963
Only one rotationally-resolved spectrum, ν17 by Henninot et al. in 1992
Figure from: J-F. Henninot et al., “The Infrared Spectrum of Trioxane in a Supersonic Slit Jet”. J. Mol. Spect. 152, 62 (1992)

5. How does CRDS work?
Piezo
Laser
AOM
Power
Time

6. How does CRDS work?
Piezo
Laser
AOM
Power
Time

7. How does CRDS work?
Piezo
Laser
AOM
Cavity on-resonance
Power
Time

8. How does CRDS work?
Piezo
Laser
AOM
AOM switched off
Power
Time

9. How does CRDS work? Cavity enhanced sensitivity
Piezo
Laser
AOM
Power
Time
Cavity enhanced sensitivity
No noise from laser power fluctuation

10. Spectrometer Layout SO2 Cell Wavemeter AOM EC-QCL Cavity Fresnel Rhomb
Polarizer

11. What do we expect to see?
Figure generated using PGopher

12. What did we see?

13. What did we see?

14. Are the spectra reproducible?
Peak positions vary by approximately ±150 MHz

15. What’s causing the uncertainty?

16. What resolution do we need?
Simulation convolved with 150 MHz gaussian
Figure generated using PGopher

17. What resolution do we need?
Simulated with 30 MHz resolution – resolved!
Figure generated using PGopher

18. Is our locked EC-QCL sufficient?
Feature <10 MHz (approx) resolved!

19. What’s next? Finish stabilizing EC-QCL
Re-acquire spectrum with better stability
Fit spectrum
New experiments:
Cyanuric Acid
Supercritical Fluid Source
Wikimedia Commons
Figures from: B.M. Gibson et al., “Development of a Sheath-Flow Supercritical Fluid Source for Vaporization of Nonvolatiles
at Moderate Temperatures”. 68th ISMS, 2013

20. Acknowledgements